Warming and hypoxia are two stressors commonly found within natural salmon redds that are likely to co-occur. Warming and hypoxia can interact physiologically, but their combined effects during fish development remain poorly studied, particularly stage-specific effects and potential carry-over effects. To test the impacts of warm water temperature and hypoxia as individual and combined developmental stressors, late fall-run Chinook salmon embryos were reared in 10 treatments from fertilization through hatching with two temperatures [10°C (ambient) and 14°C (warm)], two dissolved oxygen saturation levels [normoxia (100% air saturation, 10.4–11.4 mg O2/l) and hypoxia (50% saturation, 5.5 mg O2/l)] and three exposure times (early [eyed stage], late [silver-eyed stage] and chronic [fertilization through hatching]). After hatching, all treatments were transferred to control conditions (10°C and 100% air saturation) through the fry stage. To study stage-specific effects of stressor exposure we measured routine metabolic rate (RMR) at two embryonic stages, hatching success and growth. To evaluate carry-over effects, where conditions during one life stage influence performance in a later stage, RMR of all treatments was measured in control conditions at two post-hatch stages and acute stress tolerance was measured at the fry stage. We found evidence of stage-specific effects of both stressors during exposure and carry-over effects on physiological performance. Both individual stressors affected RMR, growth and developmental rate while multiple stressors late in development reduced hatching success. RMR post-hatch showed persistent effects of embryonic stressor exposure that may underlie differences observed in developmental timing and acute stress tolerance. The responses to stressors that varied by stage during development suggest that stage-specific management efforts could support salmon embryo survival. The persistent carry-over effects also indicate that considering sub-lethal effects of developmental stressor exposure may be important to understanding how climate change influences the performance of salmon across life stages.

中文翻译：

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发育过程中对变暖和缺氧的敏感性差异以及生命早期发育暴露的长期影响奇努克鲑鱼

变暖和缺氧是天然鲑鱼中常见的两种压力源，可能同时发生。变暖和缺氧可以在生理上相互作用，但它们在鱼类发育过程中的综合影响仍然缺乏研究，特别是特定阶段的影响和潜在的遗留影响。为了测试温水温度和缺氧作为个体和综合发育压力源的影响，在两个温度 [10°C（环境）和 14°C（温暖）下，在从受精到孵化的 10 个处理中培育了晚秋运行的奇努克鲑鱼胚胎。 ]，两个溶解氧饱和度水平 [常氧（100% 空气饱和度，10.4–11.4 mg O2/l）和缺氧（50% 饱和度，5.5 mg O2/l）] 和三个暴露时间（早期 [眼睛阶段]，晚期 [银眼阶段]和慢性[孵化受精]）。孵化后，所有处理通过鱼苗阶段转移到控制条件（10°C 和 100% 空气饱和度）。为了研究压力源暴露的阶段特异性影响，我们测量了两个胚胎阶段的常规代谢率 (RMR)，即孵化成功和生长。为了评估遗留效应，在一个生命阶段的条件影响后期性能的情况下，所有处理的 RMR 在孵化后两个阶段的对照条件下测量，急性应激耐受性在鱼苗阶段测量。我们发现了暴露期间压力源的阶段特异性影响和对生理表现的遗留影响的证据。两种个体压力源都会影响 RMR、生长和发育率，而发育后期的多种压力源会降低孵化成功率。RMR 孵化后显示胚胎压力源暴露的持续影响，这可能是观察到的发育时间和急性压力耐受性差异的基础。对发育过程中不同阶段压力源的反应表明，针对特定阶段的管理工作可以支持鲑鱼胚胎的存活。持续的遗留效应还表明，考虑发育压力源暴露的亚致死效应对于了解气候变化如何影响鲑鱼在整个生命阶段的表现可能很重要。